The Immune Privilege of the Intervertebral Disc: Implications for Intervertebral Disc Degeneration Treatment.

The intervertebral disc (IVD) is the largest avascular organ of the body. It is composed of three parts: the nucleus pulposus (NP), the annulus fibrosus (AF) and the cartilaginous endplate (CEP). The central NP is surrounded by the AF and sandwiched by the two CEPs ever since its formation. This unique structure isolates the NP from the immune system of the host. Additionally, molecular factors expressed in IVD have been shown inhibitive effect on immune cells and cytokines infiltration. Therefore, the IVD has been identified as an immune privilege organ. The steady state of immune privilege is fundamental to the homeostasis of the IVD. The AF and the CEP, along with the immunosuppressive molecular factors are defined as the blood-NP barrier (BNB), which establishes a strong barrier to isolate the NP from the host immune system. When the BNB is damaged, the auto-immune response of the NP occurs with various downstream cascade reactions. This effect plays an important role in the whole process of IVD degeneration and related complications, such as herniation, sciatica and spontaneous herniated NP regression. Taken together, an enhanced understanding of the immune privilege of the IVD could provide new targets for the treatment of symptomatic IVD disease. However, the underlying mechanism above is still not fully clarified. Accordingly, the current study will extensively review and discuss studies regarding the immune privilege of the IVD.

Dysplastic spondylolysis is caused by mutations in the diastrophic dysplasia sulfate transporter gene.

Spondylolysis is a fracture in part of the vertebra with a reported prevalence of about 3-6% in the general population. Genetic etiology of this disorder remains unknown. The present study was aimed at identifying genomic mutations in patients with dysplastic spondylolysis as well as the potential pathogenesis of the abnormalities. Whole-exome sequencing and functional analysis were performed for patients with spondylolysis. We identified a novel heterozygous mutation (c.2286A > T; p.D673V) in the sulfate transporter gene SLC26A2 in five affected subjects of a Chinese family. Two additional mutations (e.g., c.1922A > G; p.H641R and g.18654T > C in the intron 1) in the gene were identified by screening a cohort of 30 unrelated patients with the disease. In situ hybridization analysis showed that SLC26A2 is abundantly expressed in the lumbosacral spine of the mouse embryo at day 14.5. Sulfate uptake activities in CHO cells transfected with mutant SLC26A2 were dramatically reduced compared with the wild type, confirming the pathogenicity of the two missense mutations. Further analysis of the gene-disease network revealed a convergent pathogenic network for the development of lumbosacral spine. To our knowledge, our findings provide the first identification of autosomal dominant SLC26A2 mutations in patients with dysplastic spondylolysis, suggesting a new clinical entity in the pathogenesis of chondrodysplasia involving lumbosacral spine. The analysis of the gene-disease network may shed new light on the study of patients with dysplastic spondylolysis and spondylolisthesis as well as high-risk individuals who are asymptomatic.

Effects of Ginkgo Biloba Extract EGb-761 on Neuropathic Pain in Mice: Involvement of Opioid System.

Neuropathic pain is considered as one of the most difficult types of pain to manage with conventional analgesics. EGb-761 is extracted from leaves of Ginkgo biloba and has analgesia and anti-inflammatory properties. This study aimed to examine the effect of EGb-761 on chronic constriction injury (CCI)-induced neuropathic pain behaviors, including thermal hyperalgesia and mechanical allodynia, and to explore the possible mechanisms underlying this action. To this end, CCI mice were intraperitoneally injected with EGb-761 (10, 20, 40, and 80 mg/kg), and thermal hyperalgesia, mechanical allodynia, cytokines, and mu-opioid receptor expression were measured. Results showed that EGb-761 attenuated thermal hyperalgesia and mechanical allodynia dose-dependently and the best delivery time window was from day 7 to day 14 after CCI. Additionally, EGb-761 treatment significantly decreased pro-inflammatory cytokines and enhanced mu opioid receptor (MOR) expression in the sciatic nerve. Moreover, the opioid antagonist naloxone prevented the effect of EGb-761 on thermal hyperalgesia and mechanical allodynia but did not influence the effect of EGb-761 on inflammatory cytokines. In conclusion, this study suggests that the potential of EGb-761 as a new analgesic for neuropathic pain treatment, and opioid system may be involved in the EGb-761-induced attenuation of thermal hyperalgesia and mechanical allodynia. Copyright © 2016 John Wiley & Sons, Ltd.

Inhibition of the spinal astrocytic JNK/MCP-1 pathway activation correlates with the analgesic effects of tanshinone IIA sulfonate in neuropathic pain.

BACKGROUND: Neuropathic pain (NP) continues to be challenging to treat due to lack of effective drugs. Accumulating evidence elucidated that glia-mediated inflammatory reactions play a pivotal role in the introduction and development of NP. Besides, activation of the c-Jun N-terminal kinase (JNK)/monocyte chemoattractant protein-1 (MCP-1) pathway in astrocytes has been reported to be critical for spinal astrocytic activation and neuropathic pain development after spinal nerve ligation (SNL). Tanshinone IIA, a major active component of a traditional Chinese drug, Danshen, possesses potent immuno-suppressive activities. The present study was undertaken to assess whether intraperitoneal administration of tanshinone IIA sulfonate (TIIAS) has analgesic effect on SNL-induced neuropathic pain and whether the inhibition of astrocytic activation and JNK/MCP-1 pathway is involved in the analgesic effect of TIIAS. METHODS: The effects of TIIAS on SNL-induced mechanical allodynia were assessed by behavioral testing. Immunofluorescence histochemical staining was used to detect changes of spinal astrocytes and spinal pJNK expression and localization. Immunofluorescence histochemistry and Western blot analysis were used to quantify the SNL-induced spinal pJNK expression after TIIAS administration. Enzyme-linked immunosorbent assay (ELISA) was used to detect the SNL-induced spinal expression of pro-inflammatory cytokines and MCP-1. RESULTS: Our results indicated that intraperitoneal TIIAS up-regulated the mechanical paw withdrawal threshold (PWT) of NP, while astrocytic activation was suppressed and accompanied by the down-regulation of IL-1ß and TNF-α expression, as well as JNK phosphorylation in the spinal dorsal horn. Additionally, the release of MCP-1 was dose dependently decreased. After co-treatment with TIIAS and JNK inhibitor (SP600125), no significant increases in mechanical PWT and MCP-1 expression were observed compared with the TIIAS-treated group. CONCLUSIONS: The present results suggest that the analgesic effects of TIIAS in neuropathic pain are mainly mediated by the down-regulation of SNL-induced astrocytic activation, which is via the inhibition of JNK/MCP-1 pathway.

Timing of surgical decompression for traumatic cervical spinal cord injury.

PURPOSE: Although there have been numerous studies aimed at determining the effects and safety of early vs. late surgical decompression for traumatic cervical spinal cord injury, controversies still exist regarding the optimal timing of surgery for this serious spinal trauma. This study was conducted to evaluate the effectiveness and safety of early vs. late surgical decompression for lower cervical spine trauma associated with spinal cord injury. METHODS: A retrospective review of was performed on consecutive patients who underwent surgical decompression for lower cervical (C3-C7) spine trauma associated with spinal cord injury at six institutions across China from January 2007 to January 2012. These patients were analysed according to the timing of surgical intervention. The early group comprised patients who underwent surgery within the first 72 hours after being injured, whilst the late group comprised patients who underwent surgery after the first 72 hours. For analysis of neurologic improvement, patients who had completed a follow-up of at least six months were assessed. Other outcomes analysed were hospitalisation periods, complications and mortality. RESULTS: A total of 595 patients were identified (456 men and 139 women at an average age of 41.4 years), with 212 in the early group and 383 in the late group. Patients in both groups had made a significant neurologic improvement in the final follow-up, but no statistically significant difference was noted between groups. Patients in the early group had a significantly shorter hospital stay (15.4 vs. 18.3 days, p <0.001) but realised no benefits in terms of intensive care unit length of stay and ventilator days. No significant differences were identified between groups with regards complications (pneumonia, pulmonary embolism, wound infection, sepsis and urinary tract infection). Compared with the late group, the early group had a significantly higher incidence of postoperative neurological deterioration (6.6 vs. 0.7 %, p <0.001) and mortality (7.1 vs. 2.1 %, p = 0.003). CONCLUSION: The timing of surgery for patients sustaining traumatic lower cervical spine injury with neurological involvement did not affect neurological recovery. Early surgical intervention was associated with a higher incidence of mortality and neurological deterioration compared with late surgical intervention, indicating that surgery after the first 72 hours might be relatively safe.

17ß-Estradiol inhibits ER stress-induced apoptosis through promotion of TFII-I-dependent Grp78 induction in osteoblasts.

Although many studies have suggested that estrogen prevents postmenopausal bone loss partially due to its anti-apoptosis effects in osteoblasts, the underlying mechanism has not been fully elucidated. In the present study, we found that 17ß-estradiol (17ß-E2), one of the primary estrogens, inhibited endoplasmic reticulum (ER) stress-induced apoptosis in MC3T3-E1 cells and primary osteoblasts. Interestingly, 17ß-E2-promoted Grp78 induction, but not CHOP induction in response to ER stress. We further confirmed that Grp78-specific siRNA reversed the inhibition of 17ß-E2 on ER stress-induced apoptosis by activating caspase-12 and caspase-3. Moreover, we found that 17ß-E2 markedly increased the phosphorylated TFII-I levels and nuclear localization of TFII-I in ER stress conditions. 17ß-E2 stimulated Grp78 promoter activity in a dose-dependent manner in the presence of TFII-I and enhanced the binding of TFII-I to the Grp78 promoter. In addition, 17ß-E2 notably increased phosphorylated ERK1/2 levels and Ras kinase activity in MC3T3-E1 cells. The ERK1/2 activity-specific inhibitor U0126 remarkably blocked 17ß-E2-induced TFII-I phosphorylation and Grp78 expression in response to ER stress. Together, 17ß-E2 protected MC3T3-E1 cells against ER stress-induced apoptosis by promoting Ras-ERK1/2-TFII-I signaling pathway-dependent Grp78 induction.

Protective effects of myricitrin against osteoporosis via reducing reactive oxygen species and bone-resorbing cytokines.

Oxidative stress is a crucial pathogenic factor in the development of osteoporosis. Myricitrin, isolated from Myrica cerifera, is a potent antioxidant. We hypothesized that myricitrin possessed protective effects against osteoporosis by partially reducing reactive oxygen species (ROS) and bone-resorbing cytokines in osteoblastic MC3T3-E1 cells and human bone marrow stromal cells (hBMSCs). We investigated myricitrin on osteogenic differentiation under oxidative stress. Hydrogen peroxide (H2O2) was used to establish an oxidative cell injury model. Our results revealed that myricitrin significantly improved some osteogenic markers in these cells. Myricitrin decreased lipid production and reduced peroxisome proliferator-activated receptor gamma-2 (PPARγ2) expression in hBMSCs. Moreover, myricitrin reduced the expression of receptor activator of nuclear factor kappa-B ligand (RANKL) and IL-6 and partially suppressed ROS production. In vivo, we established a murine ovariectomized (OVX) osteoporosis model. Our results demonstrated that myricitrin supplementation reduced serum malondialdehyde (MDA) activity and increased reduced glutathione (GSH) activity. Importantly, it ameliorated the micro-architecture of trabecular bones in the 4th lumbar vertebrae (L4) and distal femur. Taken together, these results indicated that the protective effects of myricitrin against osteoporosis are linked to a reduction in ROS and bone-resorbing cytokines, suggesting that myricitrin may be useful in bone metabolism diseases, particularly osteoporosis.

Estrogen improves the proliferation and differentiation of hBMSCs derived from postmenopausal osteoporosis through notch signaling pathway.

Estrogen deficiency is the main reason of bone loss, leading to postmenopausal osteoporosis, and estrogen replacement therapy (ERT) has been demonstrated to protect bone loss efficiently. Notch signaling controls proliferation and differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Moreover, imperfect estrogen-responsive elements (EREs) were found in the 5'-untranslated region of Notch1 and Jagged1. Thus, we examined the molecular and biological links between estrogen and the Notch signaling in postmenopausal osteoporosis in vitro. hBMSCs were obtained from healthy women and patients with postmenopausal osteoporosis. Notch signaling molecules were quantified using real-time polymerase chain reaction (real-time PCR) and Western Blot. Luciferase reporter constructs with putative EREs were transfected into hBMSCs and analyzed. hBMSCs were transduced with lentiviral vectors containing human Notch1 intracellular domain (NICD1). We also used N-[N-(3, 5-diflurophenylacetate)-l-alanyl]-(S)-phenylglycine t-butyl ester, a γ-secretase inhibitor, to suppress the Notch signaling. We found that estrogen enhanced the Notch signaling in hBMSCs by promoting the expression of Jagged1. hBMSCs cultured with estrogen resulted in the up-regulation of Notch signaling and increased proliferation and differentiation. Enhanced Notch signaling could enhance the proliferation and differentiation of hBMSCs from patients with postmenopausal osteoporosis (OP-hBMSCs). Our results demonstrated that estrogen preserved bone mass partly by activating the Notch signaling. Because long-term ERT has been associated with several side effects, the Notch signaling could be a potential target for treating postmenopausal osteoporosis.

CK8 phosphorylation induced by compressive loads underlies the downregulation of CK8 in human disc degeneration by activating protein kinase C.

Cytokeratin 8 (CK8) is a member of the cytokeratins family with multiple functions on the basis of its unique structural hallmark. The aberrant expression of CK8 and its phosphorylation are pertinent with various diseases. We have previously shown that CK8 exists in normal human nucleus pulposus (NP) cells and decreases as the intervertebral disc degenerates. However, the underlying molecular regulatory machinery of CK8 in intervertebral disc degeneration (IDD) has not been clarified. Here, we collected NP samples from patients with idiopathic scoliosis as control and IDD as degenerate groups. We found that CK8 expression decreased in IDD with an increased phosphorylation in degenerate NP cells. Moreover, NP cells were cultured under different compressive load schemes for diverse time duration. We found that compressive loads resulted in phosphorylation and disassembly of CK8 in a time-dependent and degree-dependent manner in vitro. The activation of protein kinase C was a significant molecular factor contributing to this phenomenon. Taken together, this study is the first to address the molecular mechanisms of CK8 downregulation in NP cells. Importantly, our findings provide clues regarding a molecular link between compressive loads and CK8 alterations, which shed a novel light on the etiology of IDD.

Brain-derived neurotrophic factor stimulates proliferation and differentiation of neural stem cells, possibly by triggering the Wnt/ß-catenin signaling pathway.

Brain-derived neurotrophic factor (BDNF) has critical functions in promoting survival, expansion, and differentiation of neural stem cells (NSCs), but its downstream regulation mechanism is still not fully understood. The role of BDNF in proliferation and differentiation of NSCs through Wnt/ß-catenin signaling was studied via cell culture of cortical NSCs, Western blotting, immunocytochemistry, and TOPgal (Wnt reporter) analysis in mice. First, BDNF stimulated NSC proliferation dose dependently in cultured neurospheres that exhibited BrdU incorporation and neuronal and glial differentiation abilities. Second, BDNF effectively enhanced cell commitment to neuronal and oligodendrocytic fates, as indicated by increased differentiation marker Tuj-1 (neuronal marker), CNPase (oligodendrocyte marker), and neuronal process extension. Third, BDNF upregulated expression of Wnt/ß-catenin signaling (Wnt1 and free ß-catenin) molecules. Moreover, these promoting effects were significantly inhibited by application of IWR1, a Wnt signaling-specific blocker in culture. The TOPgal mouse experiment further confirmed BDNF-triggered Wnt signaling activation by ß-gal labeling. Finally, an MEK inhibition experiment showed a mediating role of the microtubule-associated protein kinase pathway in BDNF-triggered Wnt/ß-catenin signaling cascades. This study overall has revealed that BDNF might contribute to proliferation and neuronal and oligodendrocytic differentiation of NSCs in vitro, most possibly by triggering the Wnt/ß-catenin signaling pathway. Nevertheless, determining the exact cross-talk points at which BDNF might stimulate Wnt/ß-catenin signaling pathway in NSC activity requires further investigation.

Down-regulated CK8 expression in human intervertebral disc degeneration.

As an intermediate filament protein, cytokeratin 8 (CK8) exerts multiple cellular functions. Moreover, it has been identified as a marker of notochord cells, which play essential roles in human nucleus pulposus (NP). However, the distribution of CK8 positive cells in human NP and their relationship with intervertebral disc degeneration (IDD) have not been clarified until now. Here, we found the percentage of CK8 positive cells in IDD (25.7±4.14%) was significantly lower than that in normal and scoliosis NP (51.9±9.73% and 47.8±5.51%, respectively, p<0.05). Western blotting and qRT-PCR results confirmed the down-regulation of CK8 expression in IDD on both of protein and mRNA levels. Furthermore, approximately 37.4% of cell clusters were CK8 positive in IDD. Taken together, this is the first study to show a down-regulated CK8 expression and the percentage of CK8 positive cell clusters in IDD based upon multiple lines of evidence. Consequently, CK8 positive cells might be considered as a potential option in the development of cellular treatment strategies for NP repair.

FasL expression on human nucleus pulposus cells contributes to the immune privilege of intervertebral disc by interacting with immunocytes.

The mechanisms of immune privilege in human nucleus pulposus (NP) remain unclear. Accumulating evidence indicates that Fas ligand (FasL) might play an important role in the immune privilege of the disc. We aimed for addressing the role of FasL expression in human intervertebral disc degeneration (IDD) and immune privilege in terms of the interaction between NP cells and immunocytes via the FasL-Fas machinery. We collected NP specimens from 20 patients with IDD as degenerative group and 8 normal cadaveric donors as control. FasL expression was detected by qRT-PCR, western blotting and flow cytometry (FCM). We also collected macrophages and CD8(+) T cells from the peripheral blood of patients with IDD for co-cultures with NP cells. And macrophages and CD8(+) T cells were harvested for apoptosis analysis by FCM after 2 days of co-cultures. We found that FasL expression in mRNA, protein and cellular resolutions demonstrated a significant decrease in degenerative group compared with normal control (p<0.05). FCM analysis found that human NP cells with increased FasL expression resulted in significantly increased apoptosis ratio of macrophages and CD8(+) T cells. Our study demonstrated that FasL expression tends to decrease in degenerated discs and FasL plays an important role in human disc immune privilege, which might provide a novel target for the treatment strategies for IDD.

Insights into the hallmarks of human nucleus pulposus cells with particular reference to cell viability, phagocytic potential and long process formation.

OBJECTIVE: As a main cellular component within the disc, nucleus pulposus (NP) cells play important roles in disc physiology. However, little is known on the biologic hallmarks of human NP cells. Therefore, the present study aimed to address the features of human NP cells. METHODS: Human NP samples were collected from normal cadavers, patients with scoliosis and disc degeneration as normal, disease control and degenerative NP, respectively. The NP samples were studied using transmission electron microscopy and TUNEL assay. Pre-digested NP samples were studied using flow cytometry with PI/Annexin V staining. RESULTS: Both control and degenerative human NP consisted of mainly viable cells with a variety of morphology. Both necrosis and apoptosis were noted in human NP as forms of cell death with increased apoptosis in degenerative NP, which was further confirmed by the TUNEL assay. Phagocytic NP cells had the hallmarks of both stationary macrophages with lysosomes and NP cells with the endoplasmic reticulum. Annulus fibrosus cells have similar morphologic characteristics with NP cells in terms of cell nest, phagocytosis and intracellular organs. Moreover, NP cells with long processes existed in degenerative and scoliotic NP rather than normal NP. When cultured in glucose-free medium, NP cells developed long and thin processes. CONCLUSION: Human degenerative NP consists of primarily viable cells. We present direct and in vivo evidence that both human annulus fibrosus and NP cells have phagocytic potential. Moreover, NP cells with long processes exist in both scoliotic and degenerative NP with lack of glucose as one of the possible underlying mechanisms.

Non-fusion and growing instrumentation in the correction of congenital spinal deformity associated with split spinal cord malformation: an early follow-up outcome.

STUDY DESIGN: A retrospective case review. INTRODUCTION: To evaluate the safety and efficacy of the non-fusion technique in achieving and maintaining the proper correction for congenital spinal deformity (CSD) and allowing normal spinal growth in patients with split spinal cord malformation (SSCM). MATERIALS AND METHODS: Seven patients who had CSD and SSCM were adopted, with a mean age of 8 years. All the patients in this study received Halo-gravity traction (HGT) prior to expansion of the spine and instrumentation with vertical expandable titanium prosthetic rib, growing rod or their hybrid. Five of them underwent opening wedge thoracoplasty simultaneously. And the two patients with type I SSCM underwent bony spur excision in the initial surgery before corrective manipulation. Then all the patients received a lengthened operation every six months. Changes of their major curve and length of T1-S1 spine were measured, and complications, neurological status were recorded. All the patients were followed up with an average of 32.6 months. RESULTS: Their mean major curve improved from 90.1° to 58.6° with a correction rate of 34.9 %. The T1-S1 length increased from 26.3 to 34.7 cm at final follow-up. Especially, one of the type I SSCM patients whose neurological deterioration was found preoperatively was significantly improved. CONCLUSION: Preoperative Halo-gravity traction followed by non-fusion and growing instrumentation may be effective and safe for young children of CSD associated with SSCM. But it is an ongoing study and additional large multicenter studies are necessary to further assess the safety and efficacy of non-fusion and growing instrumentation.

Staged corrective surgery for complex adolescent kyphoscoliosis caused by back scalding during the childhood period.

INTRODUCTION: Adolescent scar contracture kyphoscoliosis is a very rare disease. METHODS AND RESULTS: Here, we present the case of a 21-year-old man who was scalded due to ebullient water when he was 10 years old. Moreover, kyphoscoliosis was found when he was 12 years old and developed rapidly. Thereafter, no management was proposed before his consultation at our center. On examination, kyphoscoliosis was detected in thoracolumbar, the trunk deviated to the right on standing view, extensive contractured scar presented on the right side of the back, abdomen, chest wall, hip, right thighs and armpit anterior, especially in the right flank. A one-stage correction was deemed too risky, we therefore released contractured scar during the first stage with the defect of soft tissue protected by vacuum sealing drainage and then performed skeletal traction with halo and bilateral femoral pins. A reasonable correction was achieved without any neurological deficits 1 month after traction. Next, a second-stage operation was taken to translate a free anterolateral thigh myocutaneous flap to overlay the extensive defect of soft tissue. 1.5 months later, a third posterior segmental pedicle screw instrumented fusion with Smith-Peterson osteotomy between T9 and L2 was performed. Postoperative recovery was uneventful and as there were no complications, he was discharged 10 days after the third surgery. At 2-year follow-up the patient's outcome is excellent with balance and correction of the deformity. CONCLUSION: Based this grand round case and relevant literature, we discuss the different options for the treatment of adolescent scar contracture scoliosis.

Schwann cell-seeded scaffold with longitudinally oriented micro-channels for reconstruction of sciatic nerve in rats.

To provide a more permissive environment for axonal regeneration, Schwann cells (SCs) were introduced into a collagen-chitosan scaffold with longitudinally oriented micro-channels (L-CCH). The SC-seeded scaffold was then used for reconstruction of a 15-mm-long sciatic nerve defect in rats. The axonal regeneration and functional recovery were examined by a combination of walking track analysis, electrophysiological assessment, Fluoro-Gold retrograde tracing, as well as morphometric analyses to both regenerated axons and target muscles. The findings showed that SCs adhered and migrated into the L-CCH scaffold and displayed a longitudinal arrangement in vitro. Axonal regeneration as well as functional recovery was in the similar range between SCs-seeded scaffold and autograft groups, which were superior to those in L-CCH scaffold alone group. These indicate that the SCs-seeded L-CCH scaffold, which resembles the microstructure as well as the permissive environment of native peripheral nerves, holds great promise in nerve regeneration therapies.

Comparison of the Clinical Efficacy of Two Reduction Methods for the Treatment of Irreducible Unilateral Subaxial Cervical Facet Joint Dislocation.

OBJECTIVE: To compare the clinical efficacy of the minimally invasive technique and the open method in the treatment of irreducible unilateral subaxial cervical facet joint dislocation (SCFD). METHODS: From March 2015 to September 2018, 62 patients with unilateral SCFD were studied. The cases were divided into 2 groups based on different surgery strategies. Thirty-one patients were enrolled in the minimally invasive surgery (MIS) group, and 31 patients were enrolled in the open surgery group. The duration of prone position operation, blood loss, and total hospitalization costs were recorded. The clinical effects were evaluated using visual analogue scale scores, the Oswestry Disability Index, and Japanese Orthopedic Association scores at each follow-up. In addition, the segmental Cobb angle and intervertebral height were recorded and compared. RESULTS: The amount of intraoperative blood loss, prone position operation duration, and total hospital costs in the MIS group were significantly lower than in the open surgery group. The visual analogue scale, Oswestry Disability Index, and Japanese Orthopedic Association scores of the 2 groups significantly improved after the operation. A satisfactory fusion rate was obtained in both groups, and the segmental Cobb angle and intervertebral height scores in both groups improved significantly. CONCLUSIONS: Minimally invasive reduction had equal clinical efficacy to posterior open surgery. However, MIS was less invasive and had lower costs. Therefore, it is a potential option in the treatment of SCFD.

[Corrigendum] Anti­osteoporotic effects of tetramethylpyrazine via promoting osteogenic differentiation and inhibiting osteoclast formation.

Subsequently to the publication of the above paper, an interested reader drew to the authors' attention that, in Fig. 2A on p. 8311, portraying the results of immunostaining experiments for osterix, the 'GIOP' and 'GIOP+TMP (20)' data panels contained overlapping data, such that these images were derived from apparently the same original source, where they were intended to show the results from differently performed experiments. Moreover, in Fig. 3A on p. 8312 showing the results from ALP staining and Alizarin Red S staining experiments, two pairs of apparently overlapping data panels were identified in the Dex 106 M / TMP 50 µM, 100 µM and 200 µM data panels. After having re­examined their original data, the authors have realized that the data featured in Figs. 2A and 3A were assembled incorrectly in these figures. Revised versions of Fig. 2 and 3, now containing replacement data for the experiments shown in Figs. 2A and 3A, are shown on the next page. Note that these errors did not adversely affect either the results or the overall conclusions reported in this study. All the authors agree with the publication of this corrigendum, and are grateful to the Editor of Molecular Medicine Reports for allowing them the opportunity to publish this. They also wish to apologize to the readership of the Journal for any inconvenience caused. [Molecular Medicine Reports 16: 8307­8314, 2017; DOI: 10.3892/mmr.2017.7610].

Deregulated miR-155 promotes Fas-mediated apoptosis in human intervertebral disc degeneration by targeting FADD and caspase-3.

The role of apoptosis in the pathogenesis of intervertebral disc degeneration (IDD) remains enigmatic. Accumulating evidence has shown that the apoptotic machinery is regulated by miRNAs. We hypothesized that miRNAs might contribute to apoptosis in IDD. We have found that 29 miRNAs were differentially expressed and miR-155 was down-regulated in degenerative nucleus pulposus (NP). The deregulation of miR-155 was further verified using real-time PCR (0.56 fold, p < 0.05). Bioinformatics target prediction identified FADD and caspase-3 as putative targets of miR-155. Furthermore, miR-155 inhibited FADD and caspase-3 expression by directly targeting their 3'-UTRs, which was abolished by mutation of the miR-155 binding sites. In vitro up-regulation of miR-155 in human NP cells by transfection with lentiviral pre-miR-155 resulted in repression of FADD and caspase-3; whereas knockdown of miR-155 with lentiviral antigomiR-155 led to over-expression of FADD and caspase-3. Also, Fas-mediated apoptosis was increased when antagonizing miR-155 and decreased when using pre-miR-155 in human NP cells. In addition, we presented direct evidence of NP cells undergoing apoptosis in IDD tissues using transmission electron microscopy analysis. Moreover, a combination of in situ hybridization (ISH) and immunohistochemistry (IHC) revealed that miR-155 expressed in the cytoplasm of human NP cells with reverse correlation with FADD and caspase-3. In summary, this is the first study addressing the underlying mechanisms of IDD in terms of apoptosis and miRNAs. Furthermore, caspase-3 is identified as a novel target of miR-155. Our results suggest that deregulated miR-155 promotes Fas-mediated apoptosis in human IDD by targeting FADD and caspase-3, implicating an aetiological and therapeutic role of miR-155 in IDD.

Calcification of the intervertebral disc and posterior longitudinal ligament in children.

STUDY DESIGN: Case report. OBJECTIVE: To report the clinical features, radiographic findings, treatments, and results of 2 children with cervical intervertebral disc calcification combined with ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA: The calcification of the intervertebral disc, which is more frequent in males with predominant localization to cervical spine, was first reported by Baron in 1924. OPLL of the cervical spine, which is found approximately in the 5th to 7th decade of life, is a disease-causing spinal canal stenosis and spinal cord compression. The etiologies of these 2 diseases still remain unclear. METHODS: An 8-year-old girl presented with progressive neck pain and complained of weakness and numbness of the upper left extremity, and a 6-year-old boy presented with complains of neck pain. X-ray, computed tomography, and magnetic resonance imaging findings of 2 patients confirmed the presence of cervical intervertebral disc calcification combined with OPLL. RESULTS: Two children were treated using conservative treatment. The girl was observed up for 2 years and the boy was observed up for 18 months, respectively. Computed tomography and magnetic resonance imaging revealed that cervical intervertebral disc calcification and OPLL at the C6/7 (case 1) and C3/4 (case 2) level have disappeared completely, only a small calcification at the C2/3 intervertebral disc remained in the second case and both of them were asymptomatic. CONCLUSIONS: Cervical intervertebral disc calcification combined with OPLL was rarely observed in children. Conservative management was carried out and the patients had a full recovery. Our experience suggests that the conservative treatment is an acceptable method.